1. Field of the Invention
This invention relates to a system for accurately timing athletic racing events, such as track meets, swimming meets and the like, for official record establishing purposes. The races to be timed are started by the firing of a starting gun and have a time sequence photographic record of the racing contestants at the finish line or at one or more intermediate timing lines, with visual indications of the elapsed time calibrated in the photograph with the images of the contestants, and, more particularly, is directed to a method and apparatus using a light-flash at the starting line and a light receptor and detector at the finish line for initiating the timer upon firing of the starting gun.
2. Description of the Prior Art
Accurate timing is required for any official recognition of running or swimming performances, and the timer must be started by automatic means. A photo finish record system currently in wide use and available under the trademark "Accutrack", produces a time sequence set of photographs of racing contestants crossing a line at which the contestants are timed in alignment with a numerical display of elapsed time expressed in hundredths of seconds. To start the "Accutrack" clock, a sound actuated switch, attached to the arm of the official race starter, was used with a wire conductor that extended from the starting line to a timing or finish line to signal the clock for starting the measurement of the elapsed time ultimately to be recorded on the photograph of the contestants crossing such line. Since the wire conductor had to be dragged to several different points on the track where the races started and finished during a single meet, this method has proved to be cumbersome and time consuming.
Another prior art method, eliminating the use of wire conductors and their attendant problems, has involved the use of radio frequency signals actuated by the sound of a starting gun. However, radio frequency interference causing spurious signals has been experienced when using radios to initiate the operation of the timer seriously affecting the reliability of the race records produced.
Sound actuation systems have also been proposed to initiate a timer. However, an extraneous sound may cause a false start of the timer. In addition, the finite speed of sound waves has a significant effect on the results recorded, particularly when times are measured to hundredths of seconds.